The present invention relates in general to an emergency control device for a fuel-dosing system of an internal combustion engine, particularly for a fuel injection system of a diesel engine. The fuel-dosing system is of the type which includes at least a sensor of the gas pedal position, means for processing the signal from the sensor, a fuel regulating device controlled by the signal processing means and including a setting mechanism for positioning both setting members of a fuel pump.
In electrically or electronically controlled fuel injection arrangements or systems as used for example in diesel engines, safety devices are known which in the case of a malfunction are activated to provide for an emergency operation of the engine and protect the same against overload. For example, from the German publication No. 1 962 570 a resetting device for a dosing member of fuel injection system is disclosed which is activated in response to the occurrence of a defect such as for example when the regulating circuit itself or a conduit from one of its sensors is interrupted. Upon the activation of the resetting device, the dosing member is adjusted so as to supply smaller amounts of injected fuel. This known device however has the disadvantage that due to the aforementioned adjusting measures in the direction to lower amounts of supply of fuel the output of the engine can be reduced to such an extent that if the vehicle operates in a difficult terrain, for example, the operation of the engine can no longer be maintained.
Accordingly there is a need for an emergency control device for fuel-dosing systems, particularly fuel injection systems which guarantees that the engine is protected under all circumstances against overspeed, that excessive doses of fuel are avoided and at the same time the controllability of the vehicle by the operator is maintained under emergency operational conditions and without larger impairment of the overall operation.